Abstract - Honey bee (Apis mellifera L.) colonies are subjected to many
persistent viral infections that do not exhibit clinical signs. The
identification of criteria that could identify persistent or latent
infections in bee colonies is a challenging task for field investigators and
beekeepers. With this aim in view, we developed a molecular method to
estimate the viral loads for six different RNA viruses in bee and mite
individuals collected from seemingly healthy colonies (360 colonies). The
data showed very large viral titres in some samples (>109 copies per
bee or mite). Discrepancies between adults and pupae viral RNA loads and, in
several instances, significant seasonal variations among viruses were
observed. The high titres of some RNA viruses recorded in mites confirm that
Varroa destructor could promote viral infections in colonies.